Method of and apparatus for the measurement of distance or time interval by the use of compressional waves in the so-called supersonic range



March 10, 1953 R. w. GOBLE 2,631,270

METHOD OF AND APPARATUS FOR THE MEASUREMENT OF DISTANCE 0R TIME INTERVAL BY THE USE OF COMERESSIONAL WAVES IN THE SO-CALLED SUPERSONIC RANGE Filed May 19. 1947 4 Sheets-Sheet 1 Record er Rucwcr Plan Bullion lndlcakor l Aim? 4 Sheets-Sheet 2 R. W. GOBLE METHOD OF AND APPARATUS FOR THE MEASUREMENT OF DISTANCE OR TIME INTERVAL BY THE USE OF COMPRESSIONAL WAVES IN THE SO-CALLED SUPERSONIC RANGE March 10, 1953 Filed May 19, 1947 March 10, 1953 METHOD OF Filed May 19, 1947 R. W. GOBLE AND APPARATUS FOR THE MEASUREMENT OF DISTANCE OR TIME INTERVAL BY THE USE OF COMPRESSIONAL WAVES IN THE SO-CALLED SUPERSONIC RANGE 4 Sheets-Sheet 3 wua wfon Ralph W. fi ble March 10, 1953 R W GOBLE METHOD OF AND APPARATU- FdR THE MEASUREMENT OF DISTANCE OR TIME INTERVAL BY THE USE OF COMPRESSIONAL- WAVES IN THE SO-CALLED SUPERSONIC RANGE Filed y 19. 1947 4 Sheets-Sheet 4 l Mk.

v I I PM; mg 57 I Ob I R fed Bloqkms I o \\\Qt y- 30 60 I oc Z9b Oonrroflcd H1153 senemkor Patented Mar. 10, 1953 ZU'NITED STATES "PTE NT 'OFFICE *lta-lph'wrGoble, Long Beach, Calif., assignor to Eastman Oil -'Well Survey Company, Denver, (1010.3 a corporation of Delaware .eyepplicauonma 19, 1947, Serial No. 749,030

9 51Claims.

ip This; invention-relates tognew and useful imp,.lprovementshin'niethodsof and apparatus for the time interval by the lmeasurement of distance or so-rcalled super- Musiof compressional waves in the --.:.sonictrange.

.Q The "invention relates particularly to methods randapparatus primarily. adapted for use in meas- ..-v...,ascertained; the results being accomplished Withtout'the use of mechanical measuring elements or I feelers or expanding arms whereby the measuring capacity ofthe device is substantially unnlimited andthe inherent. disadvantages of mechanical elements or arms areobviated.

I An'important object of the invention is to prof-videaniimproved measuring method which is particularlyuseful in measuring well bore diameters and which involves the transmission and reception ofsound waves of high'frequency in the so-called supersonic range, together with a "measurement of'the time difference or interval between the transmission of said waves and the reception ofthe associated echo or reflected waves; 'suchtime differenceor interval being rep- '.t'iresentative "or indicative ofthe distance between the point of'transmission and the point of reflec- """"tion of saidwaves, whereby said distance may be accurately measuredanddetermined.

'A'particular object ofthe invention is to protvide an improved measuringmethod which consistsLin tran'Smitting and sending out "highfre- .quencyyibrationsinto a well-bore and determinifingthe time interval required for the vibrations, Jwhichiare'reflected from the wall of said well bore, to arrive at the point of' transmission, .wherebyan accurate determinationofwvell bore diameterma'ybe made; the method being pri- .....marily useful in accurately measuring relatively small distancessuch as are encountered in well -bores,

ImgStill-anotherlobject ofathe invention is to provide .lan .improvedwmeasuring apparatus," of the character described wherein, a measuring ast, "sembly, is adapted to be -lcweredithrough a. well 2 a receive high frequency sound wave -trains, together with means for measuring the time interval between the transmitted and receiVed refiected wave; said apparatus also including means at the surface for visibly recording the-measurements'made by said measuring assembly as-it is lowered through the well bore, whereby a continuous visible indication of the well-bore diameter, is produced. 1 V

A further object of; the invention is to provide an improved apparatus, ofthe character described; wherein a sending and receiving crystal or transcender which is lowered through the well bore is utilized to transmit direct high frequency sound waves and to receive the echo or'reflected waves, with said transcender being rotated at a predetermined speed so as to continuouslyscan the surface from which the wavesare reflected; the speed'of rotation of the transcender being synchronized with the circular sweep of an indicator at the surface, whereby the pattern-:ob-

tained on said indicator provides a visualindication of themeasurement being made.

Another object of the invention is toe-provide an improved measuring assembly for an apparatus ofthecharacter described, which assembly is adapted to-be lowered'within a well boresand which-assemblyincludes a rotating sending and receiving crystal, together with a driving oscillator the latter being actuated at the frequency at which the crystal is adapted to operate, whereby maximumefficiency-or output of said crystal is assured.

A specific object of the invention-is toprovide an -improvedapparatus, of the character described, which iscapable of accurately measuring of which may be of the permanent record type,

may be simultaneously operated to visually record and indicate the measurements being made.

The construction designed to carry out'the invention will be hereinafterdescribed-together withot-her features of theinvention.

- "The invention will be more'readily understood from a reading ofthe following specification and 1by--referencetothe accompanyingdrawing wherein" an example of the invention is-sh own,

K and wherein:

"Figure 1 is a-schematic view; of a wellybore Q bore and continuouslyzoperated. tor-transmit. and :5;

.loweredavithin; said bore and the ,Igcelvlng; and ii i at nelunits. locat atcthesurfacescreen, illustrating the wave forms of the transmitted and received electrical impulses at various points or stages in the electrical circuit,

Figure 10 is an enlarged, transverse, vertical sectional view of the lower portion of the measuring assembly,

Figure 11 is a horizontal, cross-sectional view, taken on the line I ll I of Figure 10,

Figure 12 is a wiring diagram of the transmitter and transcender,

Figures 13 to 18 are face views of an oscilloscope screen illustrating the wave form of the electrical current and impulses at various points in the transmitter circuit,

Figure 19 is a block diagram of a modifledform of transmitter circuit,

Figure 20 is a'face view of an oscilloscope screen illustrating the indication which is produced .when the apparatus is employed to check cement thickness within a wellbore,

Figure 21 is a view, similar to Figure 20, showing the illustration produced when the apparatus is employed for locating perforation in the well pipe, and

Figure 22 is a view, similar to Figures 20 and 21 of an oscilloscopescreen of the indication obtained'when the apparatus is employed for locating pipe, junk or other material in the well bore.

.:In the drawings, the numeral l designates V "a well bore which extends downwardly through 1 the sub-surface strata from the ground surface.

Atransmitting assembly A, which will be hereinafter described in detail, is arranged to be lowered within the'well bore and said assembly 'is connected to the lower'end of a sinker or lowering bar H. The sinker bar is attached to the lower end of a conductor cable I2 and said cable functions to suspend or support the transmitting assembly and at the same time provides tion indicator, synchroscope and recorder are units of standard construction and the latter includes a movable tape or chart I! which is adapted to be traversed by a marking stylus H5. The stylus is electrically controlled in accordance with the operation of the transmitting assembly A and receiver B, as will be explained,

and functions to form a permanent record of the particular measurement which is being made.

The assembly A which is arranged to be lowered within the well bore l0 includes a tubular ycasing or housing 26 which has its upper end attached to the sinker bar H. A transmitter 2|, the electrical circuit of which will be hereinafter described in detail, is mounted within the tubular casing or housing 20, being supported therein upon a suitable internal annular shoulder 22. An electric motor 23 is mounted within the lower end of the housing 20 and is maintained in position bya retaining ring 24. The shaft 25 of the motor extends downwardly from the housingand has'a sending and receiving crystal or transcender 26 secured to its lower end. The electric motor 23 is coupled to the transmitter kc. to 1 megacycle.

through an inductive coupling 21 and obviously with this arrangement the parts are electrically connected while permitting the motor shaft and the crystal secured thereto to rotate with respect to the stationary transmitter. A suitable protective element or guard 28 is threaded onto the lower end of the casin or housing and protects the crystal 26 from damage as the assembly is raised or lowered within the well.

An electrical connection between the crystal 26 and. the inductive coupling 21 is made through a wire 2111. A conductor or wire 29a provides an electrical connection between the coupling 21 and the transmitter, while a conductor 29 extends from the transmitter and forms part of the cable l2 which extends to the surface equipment. As is the usual practice, the outer sheath of the cable forms the ground side of the circuit. Assuming that well bore diameter is to be measured, the transmitter 2! is operated and this will initiate actuation of the rotatin crystal ortranscender 26, whereby high frequency sound'waves in the so-called supersonic range will be generated and transmitted outwardly from the crystal. The operating frequency is subject to some variation but it has been found that satisfactory results have been obtained in the range from '500 As indicated by the dotted lines in Figure 11, the transmitted waves will travel outwardly into contact with the wall of the well bore Ill and upon striking said wall will be reflected back to the crystal or transcender 26 to vibrate the crystal. This vibration caused by the reflected waves will generate a voltage and this voltage is conducted to the surface equipment. At the time that the transmitter is operated to actuate the crystal and transmit the sound waves, a signal is conducted to the surface equipment and this transmitted impulse will appear on the screen of the plan position indicator C as well as upon the screen of the auxiliary synchroscope D.

It is noted that the usual well bore has a fluid, such as drilling mud or the well fluids therein at all times and obviously'the transmitting assembly is lowered within such fluids. It is the fluid which is present within the well bore which provides themedium through which the sound vibrations or waves are readily propagated both as to the direct, as well as the reflected or echo waves.

As the reflected or echo waves are received by the crystalZB, the voltage generated by the received waves is conducted'upwardly to the surface through the conductor 29 and this reflected or echo wave becomes apparent upon the screen of the plan position indicator C and the screen of the auxiliary synchroscope D. As will appear later, the recorder E is actuated in accordance with the transmitted and received waves and its stylus I8 is movable to indicate upon the chart the actual diameter of the well bore. Actually, all of the indicators 0, D and E provide similar information with respect to the well bore diameter.

The circular sweep of the plan position indicator C is controlled and synchronized to the .same speed ofrotation as the crystal 26 and,

' *The aiixi-liary-synchroscope Dindicates 'thein- 'stant of transmission of the-transmitted wave in the former a positive -pip= on its -screenixand indi- *cates the instant of receptionof the-reflected or echowave by a second or-snialler pip which is; P of eoursefspaced' from the first pip} Thedistance etween 'the two =pips which= are representative f the-transmitted and-=- received waves win -indicatethe time *intervaTbetweerr'the time 'of'transmission and the time"'of-'-reception.* By properly- "-'="calibrating the-distance -on the -screen of the --;synchroscop'e D; it is possible to accurately meas- --*--"ure*thedistancebetween thecrystal' ZGand the reflecting surface or wall ofthe well-bore at" that pointiormeasurement.

c-At the -same time that the-transmittedwaves :and. the: received--01 'echcr waves -are indicated 'IITOIiJTthE" units" Chanel D;." the "stylus l8 o f 'the re- "'..'-c'order'E' "is actuated to visibly recordgthediameter: as measured: by-the assembly A.";The"'po tion offthefistylus withl'respect'gto-its :chart I! l. 'isicont'roll'ed. solely in, accordance" with the time oftransmission"";and the "time" of reception of the"'waves. As .will' beiiexplained, the rotating jcrystal "sends" and receives 'aiplurality of'waves "',or"wave "trains Lduring each revolution and all ".of the sen-t and received" waves :during 'one revo- "*lutionareintegratedand averaged to actuate the "stylus and; "therefore, .the't. line formed 1 by the stylus on the chart is representative of the mean diametenof the wellborea't the point of'measurer'nent. The chart ll; of course, provides a perma'n'ent'visible record of the well bore diameter. lift is pointed out thatit is notessential. to the .p'rese'nt invention. that, the three-indicating devicesj C, D; and E. be employed since obviously anyonebf. said three devices would provide the required information with respect to the vdiameter .of.mtheawellwbore.. However,. as illustrated the j plan .position indicator furnishes .a visual indil cationTofflthe. actual cross-section of the well Whore; while the synchroscope or,.auxiliary oscilleloscope D provides-an. indicationrwhich may be x i-accurately measured at anytime toadetermine the well bore radius at any given point. The recorder E produces a permanent record of the nwellhbore diameter throughoutthe vlength or depth of said bore.

WAsuhas been stated, the sending. andreceiving cr-ystal orctranscender 26-rotates at a-predeter- (mined-speed within the wellbore duringoperar tion of the-apparatus. .7 The frequency of; the generated and transmitted sound: :waves on-wave rains is suflicient to prevent inaccurate treadngi due 120,-. the rotating :mevement :of :the crystal ecauserthe' speed of the tsound :wave transmisersionhoretraveL-as it moves frorn -the crystal to athe-wall of the well .bore 1 and then @back to-the wcrystal; is "sufficiently :great-to permit reception oof the-reflected wave or -wave-train beforelany i-Eappreciableangular movement of theorystal has ---occurred. In other wordsy-the frequency of; the .z-;transmitted+ waves is greater thantthe: speed of rlotation of-the crystal "zswhichemeans that the wave-may "be transmitted; reflected and :received .@-.;'-before 'there is any noticeable change-in the radial on angular'positionof the-rotatingcrystal. 1 "It may occur that the: assembly: A which has u the :rotating :crystal'ZG-atits lowerend'will be 1'isuspendediioff center 01"0QVJ31'C15UI18"S1C1 of the well ::bore softhat the'ecrystal 2.5 l is not-:exactly centered within f said bore. In such instance the pattern which will; appear on l the plan "position indicator will definitelyshowithar; said crystal ismfimenter 213BB2J1Se Tih1SpOtfi2$ the-center of C 6 l the screen of said indicator represents thercenter or axis of the-well boreptherefore, ifit-herscan- 'ning beam which forms the" circle-representative of the well bore is eccentricto thecenter spotythis will-indicate that the assembly A is:'not axially centered within the bore The auxiliary isynchroscope'D' will' give further indication off zany off-center position because'the distance: between thepositive pips on-this scope arerepresentative l0 of 1 the distance between the crystal "26' "and the -wall of thewell bore at the instant of measurement. It will be obvious that 'if":the'--distance between the pips remains "the -same throughout one revolution of the crystal? 6, then said crystal is in the center-0f the b0re;*'-.I-Iowever, if the distance 'between the pips on the: screem'of -the 7 synchroscopeconstantlyvaries 'during one revo- :lution of the crystal;thisihdicates that the distance between the crystaland-the wall ofsthe well bore is notthe-same during the: one rev'olution of-said crystalandthus advises theoperator that 'thecrystal is ofi-center.

' With-respect to 'therecorden- 'itha's been stated -that-it is necessarythatthe indication asire- -corded by the -moving stylus l8 be--an-average of the distances measured during one revolution of the rotating crystal. willassurethat -the =record'appearing' on th-chart1l will accurately indicate thehiean well-- bore-diameter, irre- 3o spectiveof the "position ofthe' crystal with'relation to the center of the-well bore.

The transmitter 2l'which is employed is subject to some variation andoneformof'transmitter which'may beu'sed is illustrated in Figure 12. This-transmitter includesl'aregulated'Dl. C. 1 I power supply" so which is connected. by means of a'lead-in wire 3lla-with the conductor 29;, A suitable filter 3! is connected.betweentheyline "3M and the conductor. Alternating current is conducted downwardly from the surface, and through'conductor 29-Iand1 lead-in wire 38a to J the power supply"'3fi." The power supply unit '1.furnishes power to a. blockingoscillator 32, a multi-vibrator; 33, a pulse amplifier: .34, a radio 5 frequency oscillator 35 and a radio'frequency amplifier 36,? the electrical, connections lbein F made throughv a common conductor 36b and ,branchconductorsflfitlc, 30 d and 3%., All of the elements 32 was, 'inclusive,.form a part of the .,transmittercircuit. A conductor or wir'e3l electrically ,connectsthe' alternating current lead- A. .in.wire 29 with theiblocking oscillator 32,1'whereby when the alternating currentfrom the surface l.,fiows tolthe transmitterhthe blockingljoscillator .32 is immediately ,set into operation; i It'will be inevident-thatrsinceilthe alternating current, is simultaneouslvzv conducted. ,to .the blocking, oscil- Tlator said ,current functions to synchronize the 2.11 blocking oscillator to .thefrequency of the. alterlnating current. 1

Actuation of ,the blocking. oscillator .32 -gen- V erates electrical 'pulses-which appear as shown in theoscilloscope screen patternin Figure 14 and these pulsesiare conductedthrough a 'wire 5. 32a to the multievibrator 33; wherein said pulses are shapedand the lengths ."thereof-x controlled. As the pulses arm-conducted from theamultivibrator.- 3-3 through aneonductor'33a to the pulse amplifier: 34, thEY'jEDPEZtI'I as: shown on the .oscilloscoperscreenrin IFigure :15. ii'The:pulse.-ampli her 34 has-connectionatthrough a conductor 34a with the radio:freduencyeoscillator 35:andthe amplified pulses; having the-pattern -shown on 1. the oscilloscope: screen in Figure 1116;-iunction Mite actuatea-said radioirequency oscillatosiandV thereby generate a wave train. which has the form shown on the oscilloscope-screen in Figure 17. The wave trains are conducted through a wire 35a. through the radio frequency amplifier 36 where they are amplified and then conducted through the wire 36a which connects to the wire 25a. of the transmitter. The pattern of the amplified wave trains is illustrated in Figure 18.

As explained, the wire 29a is electrically connected to the conductor 25a which extends to the crystal 26, such connection being through the inductive coupling 21.

A wire 34b has one end connected to the conductor 34a which leads from the pulse amplifier and has its opposite end connected to the radio frequency amplifier 36, whereby the amplified pulse flowing from the pulse amplifier 34 to the radio frequency oscillator 35 is utilized to gate the radio frequency amplifier. Thus, the radio frequency amplifier is not in operation and does not draw power during the intervals when pulses are not being generated. This shut-off of the radio frequency amplifier also prevents said amplifier from absorbing any power or voltage which willbe present in the conductor 29a when the crystal 26 or transcender is vibrated by the reflected or echo wave.

The wave train which is conducted to the crystal 26 will impart a vibration to said crystal so that a sound wave train of high frequency, in the so-called supersonic range, is generated and propagated outwardly from the crystal in a relatively narrow beam. As. indicated by the arrows in Figure 12, the generated wave train will travel outwardly through the fluid medium within said bore to the wall of the well bore and upon striking said wall, will be reflected back to the crystal 26. Although the crystal is rotating, the speed of travel of the wave train to the wall of the bore and back to the crystal is so much greater than the speed of rotation of the crystal that any angular movement of the head between the sending and the reception of the wave will not be noticeable. It is noted that the duration of the transmitted wave train is less than the time required for the reflection of the wave train in ascertaining the shortest distance which is to .be measured by the apparatus, and thus the transmitter is shut off at the instant that the echo or reflected wave is received.

As the reflected or echo wave train is received by the crystal 26, said crystal is vibrated to generate a voltage and this voltage is conducted upwardly through the conductor 25, coupling 2? and conductor 29a. From the conductor 2911 a connecting wire 2% carries this voltage to the con- Lductor 29 and thence upwardly to'the surface equipment. It is noted that at the time of transmission, that is, when the wave train generated by 'the radio frequency oscillator was conducted downwardly to the transmitter.

From the foregoing it will be apparent that al-- ternating current is supplied from the surface tothe transmitter 2|. Operation of the transindicator.

mitter results in the generation of wave trains which are conducted to the crystal 26 to actuate said crystal and generate high frequency sound waves which travel outwardly in the well bore. At the same time that the crystal is actuated, a signal is conducted to the surface equipment to provide information as to the instant of transmission of the sound wave. The reflected or echo wave striking the crystal is also transmitted to the surface and through the surface equipment, the time interval between the instant of transmission and the instant of reception is measured to give information as to the distance travelled by the sound waves.

The surface equipment which is employed in this apparatus is illustrated in Figure 2 and as shown therein, the alternating current for actuating the transmitter 2| is provided from a suitable power supply 40. This power supply has connection through a wire 49a with the conductor 29 which leads downwardly to the transmitter 2!. A suitable filter ll is connected in the line 40a to prevent the current which is conducted to the surface from becoming dissipated in the powersupply. The conductor 29 is connected to a receiving unit 52 which forms part of the receiver B and a suitable filter, 42a is interposed between the unit 42 and the point of connection of the line 40a, whereby the alternating current from the supply 46 is blocked from the unit. and cannot affect the same.

The transmitted wave train and the reflected or echo wave train flow from the conductor 29 within the cable l2 and just prior to their entry into the receiving unit 42 they appear as shown on the oscilloscope screen in Figure 3, the transmitted wave train being indicated by the letter T and the reflected wave train being indicated by the letter R. a

The receiving unit 42 is of the super-heterodyne type and may be a wide band amplifier, similar to the 30 and 60 megacycle strips manufactured by the Sylvania Corporation. The unit 42 functions to amplify and rectify the wave trains and gives them the patterns as shown in the oscilloscope screen of Figure 5. This pattern causes the transmitted and received wave trains to appear as positive pips and the auxiliary synchroscope D is directly connected through the wire IS with the receiving unit, whereby this type of indication is produced on the screen of said synchroscope. As has been stated, the distance between the pip representing the transmitted wave train and the pip representing the reflected received wave train is representative of the distance between the crystal 26 and the wall of the well bore. "If the sending and receiving crystal is exactly centered within the bore, this distance would be an indication of the radius of said bore.

The receiving unit 42 is connected through the wire [4 with the plan position indicator C which as has been stated, is a standard unit which may be purchased on the open market. The circular sweep of the plan position indicator is controlled and timed by the alternating current which is employed to actuate the transmitter 25. The alternating current is supplied to the plan position indicator through a wire Mb which extends from the alternating current supply wire ita to said By timing the sweep of the plan position indicator C by means of the alternating current which actuates the motor 23 of the rotating crystal 26, said sweep is synchronized with the speed of rotation of the crystal 26; therefore, the wave trains transmitted and received by the crystal 26 during one, revolution thereof will ap- 9 if pear:imaycircularlpattermupon thevscreenofctheh plan position indicator. Because of theppersistr l ence-tot vision-ether pattern will appear, on thel.. screengas 'asuhs-tantiallyw circular .line which, will be a -.crossseotional tvieweof the-walljsurface .of 1 the well .borev under investigation.

From the-foregoingitwill be seen thata visible indication is giveniby the tplancpositiont indicator C which.providesinformation as .tothe particular" cross sectionalwshape of thewell .bore. At the same ;time,v the.auxiliary. synchroscope D provides a visual vindication. of the distance between :the crystal 2-6; andntherwall oi the. bore. at any given instant Ituwillhe evident that therotationof the-crystal were. halted at any-given. timehthe, synchroscope ..indicationpermits an n accurate measurement of the distance between, the crystal 1 1 andrthelwallofthe boreatthatipointto be made, T,

Inqadpditionitot-the two concurrent indications provided by Qthelplansposition.Vindicator ,C and '2 theauxiliaryasynchroscope D, ith'elrecorderE has p, beenprovidedsonasto. produce a permanent rec- 0rd of the well bore diameter. Theflrecorder, E 1 includes theichartr. I! whichmay vhe drivenby.

a suitable .timingmotor so as to representdepth or elevation and the marking stylus, I 8 i's'moyable transversely across said chart.,, Thetimingpmotor drivesfltherchartzat a'rate correlated to the rate of lo'weringvof thelassemloly A and thus the indicationsllonpthefchart are correlated to depth; 'Ihejtransmitted wave trains and the reflected or echoiwavetrain's are conducted. from the receivingfiunitmn throughjawire 42111 to a counter; circuit, A3'which ris alsonpart of thereceiverBIj This.;counter'circuit includes. an amplifier, shaper, andlirniterunitr'efl which, isconnected by a wired lliwith'an Eccl'es-Jordantriggercircuit 45. The trigger circuit has connection through a, wire a; with thesquare Waveamplifierand limiter 46 and, thelatter, is connected through. a, conductor .tfiaf with an, integrator All" Thejintegratoris (3.011: nected throughjwireHaUyvithia vacuum .tube voltmeter 48 and the; voltmeter has direct cone nectionjwith'r'the recorder E"through,the;wire l6. EA lieg latedipower supplYSiurnishes power 2 through fsuitablaconduCtorsi to the, unitsifli to 48, "inclusive: 1' This counter? circuit may, ,form ,a. partofithe receiver IE-"illustrated in Figure. land theiwire I 6 leading from'said receiver, is the con: nection between the vacuum,.tube;voltffietenflii. I and theirecorder E.

As 'the transmitted and received wave trains;,,. flowirom" the receiver lzf'they have theipulse; pattern shown in Figure; 5, "the receiver haying. converted said": trains into ithiisfpattern The Wave trains or pulses 'thenjflow through ltheiame 7 plifleryshapergand'limiterand assume the pattern. shown in Figurefi before passingto thatri r, L circuit 45.""'Ilieitrigger circuit 45, functions to convert'thepulses into'a square wave, as 111115: .59 trated in Figure'l, and 'thissquare' wavehis con-, ductedi-tm'the" 'amplifi'e1::and limitsthei form. of .f. i said wave. *"ThefiOW is then through the integrator 45 which has' -a condenser'andresistance. arrangementrwherein the resistancecontrols the 5 discharge rateot the-"condenser; 'With this :arrangement the pulses which are "transmitted v nd. j. received during one" revolution ,of thej'crystal 2551i are utilized to charge theconclenser and through. g. the control-"of the discharge-rate of said con-t: denser by the' resistance; all of the sent andire-s. ceived pulses during one revolution are averaged so thatthe amplitude'or voltage which is conducted'to the vo1tmeter48thr0ugh the lineA'lal-W. is anaverageor mean amplitude orvoltageof the.

amplitudes producedby a l 9f, t e p s which are .lsent andrreceiyed during onegrevolution *of' said crystal. ,Manifestlyrt h v ras sa pl e w or voltage whieh is dependent upon -the-particu-=-- lar squarewaves'pro'duced during one revolution of the crystal'is.conducted to"thevacuum tubevoltmeter 483,,

It is apparent that: the amplitude" or voltage is direct ratioiorproportionto the distances between, the transmitted wave trains or -puls es and the received or echoiwa-ve" trains-or -pulses whichzare sent'and receivedduringeonerevolution of the crystal andzis-thereforean average-ofthe? distance between the: wavejtrains-or pulses sent-5 out and' receivediduring one revolution-"oftha crystal-.2 5:5: Thistaverage voltage or amplitude is utilizedito operate the vacuumtube yoltmeter whiclras has :been explained is directly-connected through" the" wire ,I 6 with the recorderyE; is well'known;thevoltmeter operates on adiiferemtiatof voltage applied thereto and asthe-average: amplitude or *voltage appliedto-the 'voltmeter upon each revolution of the crystal variesdueto variation in the-diameter of the well bore unden measurement; the-movement of the stylus ;is-vari able'in direct proportion-theretow Thechart= ll is properly calibrated in distance'and is movable by a suitable timer (not shown) at a rate corf related to the rate" of iowering of the assembly A- and thus, the movement- 0f -the; st ylus across th'e chartis an indication of the-measurement of the--- average well --bore ;diameter or cross-sectional area. ltis= obviousthat-the chart provides-a continuous record of "the spacingbetween" thecrystal-and the wallof the well=borethroughoutv eachrevolut-ionof the crystal so that acontinuous recordof the averagewell bore diameter or cross sectional area is produced:

In the operation ofthe apparatus, the'assembly" A is loweredat -a constant predetermined speed through thewell bore-1'0 and-the transmitter] l and rotating crystal-2-6 are continuously operated; 1 The speed of lowering of the assembly is synchronized with the speed -ofmovementof the recording chartlrof the recorder As'--the"==.- transmitter generates each wave train; the crystal e 23 fis -vibrated to generate and transmit 'asound wave train ofhigh frequency in 'th'e socalled--* supersonic range and'at the-'same-instahtthat the wave. train is generated and-transm-itted by-- 'the crystal, 2, signal is conducted-to the surface equipment and becomes apparent on the screensof the;plan; positionaindicatomc and theauxiliary synchroscopelsD.

Theewave. train generated; by. .the crystal; 26 -2 travels :radially outwardlyzztherefrom.rand strik the walLof the well borenandlis.immediatelyreaaa flected-back and-is-received eby saiducrysta-lrs Ase hast-been noted the timeantenval oftransmissio is such that; transmissionzis shut-01f: prior to th reception of .the reflected or echo; wavezanm thu the crystal alternately: .sendsa-andwrecei-ves: their wave trains The reception of ;the refiected or: echo .wave train is then conductedto the surf-ac and also. appears on the-screensaofgxthe plan Desi tion indicators C andtthewauxiliary synchroscope; l). The frequency of the transmitted Wavetrains: 1s so'much iaster than thespeed-oft rotation of; the crystal 26 thateachwave train isrsent andar ceived by the crystal before said--cryst-alrhas .10 tated any" appreciable orinoticeable amonntexAs the crystal rotates the; successive -;intermittentl transmitted; wave trains scan the. entire wall'sur-v facepf the well ,.bore.- \.As .has tbeen-statedwth ,synchroscoperD Lp10yides,';an mdicatimhofwthgj ace 1,270

ll actual distance between the crystal and the refleeting wall surface at any given instant. The plan position indicator, because of the fact that its circular sweep is synchronized to the speed of rotation of the crystal, provides an indication of the cross-sectional shape of the well bore.

In addition to the two visual indications which are produced by the plan position indicator and the auxiliary synchroscope D, the recorder E is included in the apparatus. This recorder has its stylus I8 actuated in direct proportion to the average distance between the crystal 26 and the wall of the well bore during each revolution of said crystal. The stylus is controlled in its movement by the counter circuit 43 which functions to convert the electrical pulses into amplitude or voltage which is directly proportional to the time interval between the periodic or intermittent sent and the received waves. As has been explained, the counter circuit functions to average all of the distances measured during one revolution of the crystal and this average is transposed into amplitude or voltage which operates the stylus l8. Therefore, as the stylus moves over the chart I! it provides a permanent record or indication of the average diameter or cross-sectional area of the well bore.

It has been noted that the invention is not to be limited to the use of the three indicating or recording means C, D and E for obviously any one or all of these units maybe employed.

The apparatus has been described as measuring the average diameter or cross-sectional area of a well bore but said'apparatus may be employed forother purposes. For example, in many instances it is desirable to deter-mine the thickness of a cement wall which has been placed behind a well casing. By lowering the assembly A into position within a well casing having cement behind the same, a double line reflection or echo would be obtained. The indication-received on the plan position indicator C is illustrated in Figure 20, wherein the inner circular line 50 represents the inner wall of the cement and the uneven, generally concentric line indicates the outer wall of said cement. An indication of this character obtained on the plan position indicator would clearly show the thickness of the cement surrounding the casing at any given depth or elevation within the well bore.

The apparatus could also be employed for cating perforations within a well casing and in such instance, an indication on the screen of the plan position indicator 0, as shown in Figure 21, would be obtained. In this case the inner wall of the pipe is represented by the line 52 with the outer wall of said pipe being represented by the line 53. At those points where perforations occur breaks 54 in the lines 52 and 53 would appear. The value of this information as to the exact location of perforations is obvious.

Stillanother use to which the apparatus may be put is illustrated in Figure 22 where the screen of the'plan position indicator C provides an indication locating therposition of a broken section of pipe within a well bore. In this illustration, the generally circular line 55 is representative of the well bore. The smaller circular indication 56 is representative of the broken section ofpipe which is lying to one side of the well bore. This pattern will be produced because of the several reflected or echo waves which would be'produced under these conditions. It is evident that many other purposes for the apparatus in V measuring distances or locating material within a Well bore may be found.

It has been previously pointed out that the particular transmitter which is illustrated in Figure 12 is subject to variation and that other types of transmitters may be employed. In Figure 19, a modified form of transmitter is shown. This circuit includes a blocking oscillator 32 which is connected to the conductor 29 through a wire 31'. In place of the various units 33 to 36 shown in the transmitter of Figure 12, a controlled pulse generator 60 is provided. This generator is connected through a wire 60a with the blocking oscillator 32. A regulated power supply 30' which has connection with the conductor 29 supplies power to the oscillator 32' and controlled pulse generator 65 through wires 60b and 600. The pulse generator has connection with the wire 35a and conductor 29a which leads to the crystal and is also connected through wire 2912 back to the conductor 29. Power to the motor 23 of the sending and receiving crystal 26 is supplied as in the first form through the wire 23a.

7 In this modified form of arrangement, the electrical pulses originating in the blocking oscillator circuit and controlled by the pulse generator 60 are utilized to shock excite the crystal [9. This shock excitation generates the high frequency sound waves or wave trains which are propagated outwardly from the crystal 26. The reception of the reflected or echo waves or wave trains by the crystal is carried out in the same manner as has been described with reference to the first form of transmitter. The surface equipment will also be identical to that previously described. It will be evident that the transmitter illustrated in Figure 19 is a simplified type but the basic operation of the apparatus remains the same.

From the above it will be seen that an apparatus capable of accurately measuring extremely small distances is provided. The sound Waves or Wave trains which are generated are of high frequency and are preferably within the so-called supersonic range which makes possible the accurate measurement of the smaller distances. The surface equipment provides visual indications which are representative of the time interval between the instant of transmission of the waves or wave trains and the instant of reception of the reflected waves or wave trains and it is manifest that by determining this time interval, an accurate determination of actual distance between the sending crystal and the surface from which reflection occurs may be made. The particular type of transmitter is subject to variation and so long as said transmitter generates a pulse capable of operating the crystal at the desired frequency, the purposes of the invention may be accomplished. As has been stated, the apparatus is not to be limited to the use of the three surface indicators since the desired information can be obtained by employing only a single indicating unit at the surface.

The foregoing description of the invention is explanatory thereof and various changes in the size, shape and materials, as well as in the details of the illustrated construction may be made, within the scope of the appended claims, without departing from the spirit of the invention.

What I claim and desire to secure by Letters Patent is:

1. An apparatus for determining the cross-sectional area of a well bore including, a transmitting assembly adapted to be lowered within a well bore and having means for continuously transmitting a plurality of series of supersonic wave trains radially outwardly toward the wall of the well bore, said assembly also having means for receiving each wave train after it has been reflected from the wall of the bore or from the surface of an object present in said bore, means for continuously rotating the transmitting assembly to continuously vary the direction of transmission about a point within the well bore, whereby the series of wave trains continuously scan the wall surface of said bore, means electrically connected with the transmitting assembly for determining the time interval between the instant of transmission of each wave train and the instant of reception of the reflected or echo wave train, means at the surface of the well bore electrically connected to the transmitting assembly for transposing the time interval determinations into visual indications of the actual distance between the point of transmission of each wave train and the surface from which said wave train is reflected, and a plan position indicator at the surface of the well bore which is actuated by the transmitted and received wave trains to produce a visual indication of the crosssectional area of the well bore.

2. An apparatus as set forth in claim 1, wherein the means for transmitting the wave train and means for receiving the reflected or echo wave train is a single crystal element which is electrically coupled to and forms part of the transmitting assembly.

3. An apparatus for determining the crosssectional area of a well bore including, a transmitter assembly adapted to be lowered through the Well bore at a predetermined rate to traverse said bore, said assembly comprising means for generating electrical wave trains at periodic intervals, and a constantly rotating sending and receiving crystal electrically coupled to and actuated by the generating means for continuously transmitting supersonic wave trains outwardly from the crystal in constantly changing radial directions, said crystal also functioning to receive said wave trains after they have been reflected from the wall of the well bore, means electrically connected to the transmitting assembly for determining the time interval between the instant of transmission of each wave train and the reception of that wave train after it has been refiected from the wall of the well bore, means for rotating the sending and receiving crystal at a speed of rotation which is less than the frequency of the transmitted sound wave trains, whereby each wave train may be transmitted, reflected and received before any appreciable change in angular position of said rotating crystal has occurred, and a plan position indicator at the surface of the well bore which is actuated by the transmitted and received wave trains to produce a visual indication of the cross-sectional area of the well bore.

4. An apparatus as set forth in claim 3, wherein the circular sweep of the plan position indicator is controlled and synchronized to the same speed of rotation as that of said crystal, whereby the pattern which appears upon said plan position indicator is substantially a cross-sectional view of the area of the well bore.

5. An apparatus as set forth in claim 1, together with electrical means for averaging the measured time intervals throughout each revolution of the sending and receiving crystal and means for utilizing this average measurement for actuating the means for transposing said measurement into visible indications of distance.

RALPH W. GOBLE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,121,411 Schroder June 21, 1938 2,156,052 Cooper Apr. 25, 1939 2,190,686 Slichter Feb. 20, 1940 2,251,817 Athy et al Aug. 5, 1941 2,333,688 Shepard Nov. 9, 1943 2,368,532 Fearon Jan. 30, 1945 2,398,562 Russell Apr. 16, 1946 2,408,458 Turner, Jr. Oct. 1, 1946 2,415,636 Johnson Feb. 11, 1947 2,456,598 Schuck Dec. 14, 1948 2,460,316 Trent et a1 Feb. 1, 1949 FOREIGN PATENTS Number Country Date 546,202 Great Britain July 2, 1942 

